Hollow core optical fibre

Abstract

A hollow core optical fibre comprises a tubular jacket; a cladding comprising a plurality of primary capillaries spaced apart from one another in a ring and each bonded to an inner surface of the jacket at a peripheral location around the circumference of the jacket; and a hollow core formed by a central void within the ring of primary capillaries; wherein the cladding further comprises, within each primary capillary, two secondary capillaries and no more, the two secondary capillaries spaced apart from one another and each bonded to an inner surface of the primary capillary at an azimuthal location around the circumference of the primary capillary which is displaced from the peripheral location of the primary capillary.

Description

BACKGROUND OF THE INVENTION[0001]The present invention relates to hollow core optical fibres.[0002]Classes of optical fibre include hollow core fibres, in which light is guided along a longitudinal hollow void forming the fibre's core by an optical guidance mechanism enabled by the presence of a structured arrangement of longitudinal cladding capillaries surrounding the void. Various configurations for the cladding capillaries are known, producing different guidance mechanisms. An example is hollow core photonic bandgap fibre (HCPBF, alternatively hollow core photonic crystal fibres, HCPCF), in which the cladding comprises a regular closely packed array of many small glass capillaries from which a central group is excluded to define a substantially circular hollow core. The periodicity of the cladding capillary structure provides a periodically structured refractive index and hence a photonic bandgap effect that confines a propagating optical wave within the core.[0003]In contrast t...

AI Technical Summary

Benefits of technology

The patent describes a new type of optical fibre that has a hollow core and a cladding made up of several layers. The fibre has a unique structure with two secondary capillaries for each primary capillary, which helps to improve its performance. The text also describes methods for making this new fibre using a preform or cane. The technical effect is to provide a new optical fibre with improved properties that can be used in various applications.

Problems solved by technology

For telecommunications uses in particular, low optical loss (being the fraction of propagating light lost per unit length of propagation, typically per kilometre) is critical, and loss levels achieved thus far with hollow core fibres are not yet fully competitive with the performance available from solid core fibres.

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